Big Idea:
Because students understand the motion of molecules and the effects of heat, they will be able to explain how a thermometer works.

Teacher Tip: This lesson is designed to prepare students for the states of matter phase changes lab. In order to perform the steps in the lab, students need to be familiar with using and reading a thermometer to find temperature of various substances. This lesson addresses NGSS SP4 as students will be collecting and interpreting data using a thermometer. There is a small amount of prep and materials needed for this lesson. You will need 3 cups of water at different temperatures and a thermometer for each small group. I usually put ice in one cup, have room temperature water and then boiled water in a cup, to vary the temperature.

To begin the lesson, students will observe an image of a thermometer on their student notes sheet and will use their prior knowledge and experience to answer the following prompt individually, in writing:

What does the object in the picture above measure?

After 2-3 minutes, I will ask a few students to share their responses, listening to the reaction of other students. If a student should say something incorrect, other students will usually shake their head or say "no" and I will ask them to explain why they are in disagreement.

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This next section is for students to explore their knowledge of the thermometer. I ask them to measure the temperature of the liquid inside the cup on their table (at this point I would take the room temperature water and place it on their table along with the thermometer). They work together with their small group to determine the temperature.

This is especially rich in dialogue as students who do know how to use thermometer will often take charge and direct the other students in the process. For those who are sitting back, I may ask them, "what should he do next?"

After 7-8 minutes, students should have measured the temperature of the liquid and have recorded their answer in the notes sheet. Most students will not remember to put the unit (celsius) and if they do, they will use fahrenheit.

Students will now take the time to write down the procedure, or the steps they took, to find the temperature of the liquid inside the cup using the thermometer. They will do this together as a small group, but will each, individually record the steps in their notes sheet.

After a few minutes, I will ask 2 groups to share their responses, writing the procedure on the SMART board for reference.

If no one has suggested it, I will add that you know to take the reading when the liquid inside the thermometer has stopped moving.

During the time the students are writing their procedures, I am placing the 3 different cups of liquid on their tables for this next step of the lesson.

Students will now use their procedures to find the temperature of three different liquids. They find the temperature and record their data in their notes sheets. As students notice, for example, the liquid in the thermometer rises or falls, I ask them to explain what causes this. They should be able to say something about the particles in the liquid inside the thermometer - they they get heated or cooled and move up or down the tube on the inside the thermometer.